Project VLCLighting – Visible Light Communications for LEDbased Public Lighting Systems
Acknowledgements: This work is funded by FCT/MEC through national funds and when applicable co-funded by FEDER – PT2020 partnership agreement under the project UID/EEA/50008/2013.
Project VLCLighting is a collaborative research project on Visible Light Communications (VLC), aiming at the exploitation of VLC concepts, for broadcast services, in lighting infrastructures. It is being developed by the Integrated Circuits and Mobile Network groups in Instituto de Telecomunicações, Aveiro site, in Portugal, and expects to deliver a VLC demonstrator transmitting video and data in real-time by the end of 2016. Another main goal is to develop this system to be modular in order to enable collaboration with other groups with interest in this field, offering the academic community a real-time test bed to evaluate the performance of different modules, algorithms and optical front-ends, which is currently not available. This means that the transceiver’s architecture must be modular in order to ease the adding/removing of modules developed by different research teams. Different modulation schemes and signal processing units can therefore be easily tested, their performance evaluated and compared to alternative solutions. To this end, the interface between main blocks includes elastic buffers that implement an asynchronous handshake protocol. As long this architecture is respected, it is very straightforward to add/remove blocks without concerns about synchronism and latencies.
The VLC transceiver is being implemented in a Xilinx Field Programmable Gate Array (FPGA). Beyond usual advantages of prototyping with FPGAs, it is especially suited for this project because of: i) the availability of system level tools (e.g., Xilinx System Generator) that eases the hardware design learning curve, especially for researches used to MATLAB and Simulink for algorithm design; ii) the easiness of introducing new modules, and testing their performance in simulation, co-simulation and real-time; iii) the availability of sophisticated hardware debug tools, such as Xilinx ChipScope Pro; iv) the reasonable cost when compared to existing real-time VLC demonstrators (relying on arbitrary waveform generators); and finally, v) the possibility to integrate the transceiver with a microprocessor with Linux support (e.g., Microblaze) which enables full system integration with high level data services. Figure 1 depicts the software development flow and Xilinx tools used in this test-bed. Processing units are developed in System Generator; the transceiver’s integration with MicroBlaze and ChipScope modules is performed in EDK; and finally, synthesis and implementation steps are performed in ISE.
The test-bed system level architecture is depicted in Figure 2. It comprises the VLC transceiver implemented in the FPGA (Xilinx ML605 or KC705 development boards), a DAC/ADC board from Analogue Devices (AD-FMCOMMS1-EBZ, in baseband configuration) and an optical front-end. The optical transmitter can be based on a single LED or a LED matrix using Optical Digital to Analog Conversion (ODAC) concepts, while the receiver is currently based on a Hamamatsu C12702 receiver module. The VLC transceiver and analog modules are easily configured via MicroBlaze, using a MATLAB Graphical User Interface (GUI). For debugging and testing purposes, ChipScope Integrated Logic Analyzers (ILA) modules are used.
For additional information, please contact Dr. Monica Figueiredo (firstname.lastname@example.org).